The conventional wisdom regarding the value of a social media follower is that once someone subscribes to you, be it via a Twitter follow of a Facebook like, you can repeatedly message to them until they decide they’ve had enough. While subscribed, of course, they can share your content, a major plus. But, being able to message repeatedly as a result of a Facebook like or Twitter follow is an extremely valuable tool, especially for political campaigns who would have had to spend valuable and limited cash to do so otherwise.

If the assumption about repeated messaging holds true, then the timing of the Obama campaign’s ad buy actually looks quite odd. To make such a significant investment so close to election day seems to discount the benefits of repeat social messaging. After all, had the Obama campaign spent the Facebook ad money earlier, the effectiveness of three months of repeat messaging surely would have trumped the one month they will now get with this campaign.

If there is a conclusion to be drawn here, it’s that the Obama campaign understands that people who “like” their campaign’s Facebook page, and hence subscribe to updates, tend to hide those updates (or unsubscribe) after a very short period of time. The campaign is therefore, in its mind, spending the money at the optimal time where they think they will get the most bang for their buck: four weeks before election day.